Connecting to MySQL using Java By:

– Required to use Java.sql so that we can use Connection and Queries using strings. – Javax.swing.* needed for components used in GUI – Java.io for input and output functions. – Java.awt.* for interactivity with the GUI.

Connection class comes from Java.sql.* library. Used to establish a connection with the database and starts with a null connection until told to connect. Connecting to the database is enclosed inside a try block to catch exceptions in connecting, so program doesn’t crash and problems can be fixed later.

ActionPerformed grabs the actions from buttons, and depending on which button is clicked, uses the appropriate action. There are only 2 types of statements in SQL, update type statements and Query type statements. An Update statement is used to modify the database in some way. Update is a simple process, the function returns an integer of the number of columns returned, or -1 if the update failed.

A query type statement is used when we are retrieving data from the database A ResultSet, that executeQuery returns, is the data retrieved in a 2 dimensional array similar to the format of a database. A ResultSet can contain multiple data types. In this case, it cannot be accessed as a normal 2 dimensional array and we have to use special get functions to retrieve the data.

The amount of columns returned by a query statement cane be retrieved using the functions of a ResultSetMetaData., this holds information about the data returned. For example: the name of the column, how many columns, and the SQL data type of the column. All data retrieved in this program is used as strings to be printed to the TextArea in the GUI. If we wanted to actually use the data for specific purposes, there are other functions to get the true data type, rather than strings. Rs.next() points returns a true if there is another row of data in the 2 dimensional array. It also move the ResultSet to that row for retrieval with a ResultSetMetaData data type.